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Sainsbury's brand new store in Weymouth has all the bells and whistles that you would expect of a £40m retail development.

Yet it's the store's sustainability credentials that make it stand out. Pitched as the "most sustainable Sainsbury's in the country", the 3,716m2 facility boasts an array of eco-innovations, from its insulating timber roof to more than 100 "prismatic" rooflights.

According to Paul Crewe, Sainsbury's head of sustainability, energy and efficiency, where the Weymouth store really pushes the boundaries is in its approach to water management. "Our aim is to reduce the consumption of our operations [in Weymouth] by 70% relative to stores of a similar size in 2005/2006", he explains.

The remaining 30% that the retailer requires for operational use is then offset through a water saving partnership with two local schools. These external savings equate to Sainsbury's total water consumption, enabling the company to claim its water footprint is neutral.

Water neutrality

Efforts by Sainsbury's to develop a "water neutral" store represent an impressive managerial effort. The Weymouth site is equipped with an extensive rainwater harvesting system, which provides much of the water for the store's car washing and toilet facilities. Added to this is a gamut of water-efficient technologies: pre-rinse spray taps, low-flush toilets, waterless urinals, low-flow percussion taps and so forth.

Sainsbury's has been gradually rolling out similar efficiency measures across its estate, with the result that its water consumption is now 50% lower (on per square metre basis) than in 2005/06. In volume terms, that's a saving of almost 1bn litres a year – an achievement recently noted by the Climate Trust, which awarded the UK supermarket its Water Standard.

Other large supermarkets are following suit. UK supermarket chain Morrisons, for instance, has installed over 700 water meters across its property estate since 2011. Marks and Spencer has reduced the water footprint of its operations by 18% compared to 2006/07 levels through efficiency measures. While Waitrose has installed shut-off valves to prevent water being used when its stores are unoccupied.

What is different in the Weymouth case is that Sainsbury's water neutral ambition is pushing it to look for external as well as internal efficiencies. "It's ground breaking in that sense that Sainsbury's is looking out of their immediate operational use of water and investing in the local community to drive water savings", notes Jonathan Clarke, head of systems and services at Anglian Water.

In the Weymouth case, the retailer has achieved this by installing water meters in two neighbouring schools, which log water flows and identify leakages. The devices are the handywork of Waterscan, a specialist provider of water management services. The schools' leaking pipes are now fixed, saving 4.5m3 of mains water each day.

Large-scale adoption still to happen

The notion of water neutrality has been kicking around in management circles for a while. The Environment Agency, which is among the chief champions of the idea, issued an extensive report on the theme back in 2007. Even so, the idea has not been hugely adopted by the business world in the UK, according to a spokesperson for the Carbon Trust.

It's understood that Sainsbury's is the only UK supermarket currently experimenting with the concept. That said, the retailer isn't jumping in. It is currently trialling the scheme in selected new stores and has yet to make a water neutral commitment for its entire portfolio.

So why doesn't water neutrality have wider uptake? Partly because the UK, unlike many developing world countries, isn't suffering from sustained water stress yet – the droughts of 2012 excepted. Furthermore, not all companies have major water footprints. Water use in professional service industries such as advertising or banking is far lower than sectors like manufacturing and agriculture.

Even so, the principle of going water neutral – or even 'net positive', as in the case of Coca Cola – marks an "honourable goal", according to Piers Clark, commercial director at UK utility Thames Water. As first steps go, companies should source "reliable, robust data" about their water use and then determine "what good looks like" for their specific context, he advises.

Clark cautions businesses to take a common sense approach thereafter. "You can, for example, recover water by taking dirty water and cleaning it up for non-potable uses, but doing that can be quite energy intensive [and] might actually increase your carbon footprint", he notes.

There's another, more significant sting in the tail. A company's water impacts don't unfold solely within its immediate operations. There are indirect impacts to consider too – some of them very large. Take Tesco. The UK's largest supermarket chain freely admits that the water embedded in the products on its shelves is 30 times higher than the total water it uses to run its stores, offices and distribution centres.

Sainsbury's doesn't hide the fact that its primary water impacts lie outside its four walls. Look at its 20 sustainability goals for 2020 and you'll see a commitment to securing its supply chain against water vulnerability. But with thousands of products coming from hundreds of different corners of the world, the task of going neutral on indirect water impacts is fiendishly difficult.